Dressing mechanism



June 26, 1945. L. o. CARLSEN DRESSING MECHANISM Filed March 1, 1943 s Sheets- Sheet 1 Summer (LEONARD 0. cneLsew June'Zfi, 1945. 1., OQCARL SEN DRESSING-MECHANISM Filed March 1, 1945 8 Sheets-Sheet 2 June 26, 1945. o. CARLSEN DRESSING MECHANISM Filed March 1, 1943 8 Sheets-Sheet 3 I Ihwentor LEON/9RD 0. CHRLSEN June 26, 1945. L. o. CARLSEN 2,378,980

' DRESSING MECHANISM I Fi led March 1, 1943 8 Sheets- Sheet 4 Lam/MP0 0. .CHRLSEN 3nnento'r 8 Sheets-Sheet 5 3nvent r LEONARD 0. CHELSE/V I g v I mttomeg June 26. 19451 L. OJCARLSEN DRESSING'MECHANISM File d March 1, 1 943 7 8 Sheets-Sheet 6 my, 24 I I i'mv'entor LEON/9RD o. CHRLSEN Gttomeg June 26, 1945. o. CARLSEN 2,378,980

DRESSING MECHANISM Filed Maich 1, 1943 s Sheets-Sheet 7 Zhmeutor LEON/9RD 0. CHRLSE/V June 1 v 1... o. CARLSEN 2,378,980

DRESSING MECHANISM Filed March 1, 1943 a sheet s sheet 8 3l 1ventor Lao/m ED 0. CARL 551v (Ittprneg Patented June 26, 1945 DRESSING MECHANISM Leonard 0. Carlson, Rochester, N. Y., assignor to Gleason Works, Rochester, N. Y., a corporation of New York Application March 1, 1943, Serial No. 477,561

26 Claims.

The present invention relates to grinding machines and to dressing mechanisms for such machines. In particular, the invention relates to machines for grinding spiral bevel and hypoid gears in a generating operation, and to dressing mechanisms for machines of this type.

In spiral bevel and hypoid gear grinders of the generating type-a rotary annular grinding wheel is used. Thewheel is mounted on an oscillatory cradle that is rotated in time with the rotation of the work to produce the generating motion and cause the wheel to grind correct tooth profiles on r moreover, the dressing mechanism has had. to.

be adjusted to different positions around the Wheel so as to avoid interference with the work, and even then, difliculty has been experienced on some jobs in obtaining suflicient clearance between the dressing mechanism and the work dur-.

ing grinding. i

For grinding some forms of gears, particularly gears such as are used in aeroplane drives, it is necessary to grind the bottoms of the tooth spaces as well as the sides of the teeth. The purpose of this is to have the sides and bottoms of the tooth spaces join one another smoothly and avoid any tendency for cracks to develop at the junctures of the sides with the bottoms of the-teeth when the gears are under load. The grinding wheels used accordingly must be dressed with rounds at the junctures of their sides and their tip so that they will grind well-rounded fillet curves in the bottoms of the tooth spaces of the gear. Where the wheel is to grind both sides of a tooth space simultaneously, it is customary to dress the top of the wheel to an elliptical shape, for a wheel so dressed will grind a fairly flat bottom in a tooth space with the desired wellrounded fillet curves at the junctures of the sides and bottoms of the tooth spaces. When one side of a tooth space is ground at a' time, however, the elliptical shape is not satisfactory for then a ridge will be left in thebottom of each tooth the ellipse which is formed by the wheel in grinding the opposite side of the tooth space. One object of the present invention is to provide a generatingtype of gear grinder on which the dressing mechanism is so mounted as readily to clear the work regardless of the position of the wheel in its adjustment for spiral angle.

Another object of the invention is to provide a generating type machine for grinding tapered gears, in which the weight of the dressing mechanism may be supported independently of the cradle, so that the cradle may be operated at high speed for generating the tooth profiles without the dressing mechanismin any way effecting its balance or tending to cause setting up of vibra- .tions.

Another object of the invention is to provide a generating type of gear grinder which will permit of guarding the .wheel very simply and completely in any adjusted position. 7 V

A further object of the invention is to provide a generating type of gear grinder in .Whichthe dressing mechanism is'mounted so as to be moved away from the wheel after dressing so that it is entirely out of the way during grinding and can neither interfere with the work nor with the guarding of the wheel.

Another object of the invention is to provide a dressing mechanism. whichhas side and tip dressers and in which the mechanism for actuating the dressers is, simplified very much as compared with previous forms of such dressing mechanisms. To this end, it. is a purpose of the invention to provide a'dressing mechanism in which the side and tip dressers can be actuated simultaneously by movement of a single hydraulically operated piston.

Another object of the invention is to provide a generating type of gear grinder in which the dressingmechanism is so mounted as to reduce the length of the flexible hoses required for conducting the'motive'fluid to and from :the actuating parts of the dressing mechanism, and bring these hoses together so that they can readily be guarded.

Still another object of the invention is to provide a dressing mechanism with which the wheel space where the ellipse, which is formedby the I wheel in grinding one side of a tooth space, joins may be dressed to have a fiat tip surface but with rounds joining the tip surface with the sides.

Another object of the invention is to provide a dressing mechanism which is movable to an inoperative position clear of the wheel, after dressing is completed, and in which the movement of the dressing mechanism to inoperative position may be employed to dress a flat tip surface on the wheel.

A further object of the invention is to provide a dressing mechanism in which the tip of the wheel may be dressed either with rounded or a flat surface.

Another object of the invention is to provide a gear grinder in which the wheel is fully guarded during grinding-I but inwhieh a pa'rtbf the guax'i'd i opened automaticallywhenthe dressing-mechanism is moved to operative position in order to permit the dressing tools to engage the wheel, arid in which the guard is closed automatically (when the dressing mechanism is moved to inoperative position.

Another object of the invention is to provide a gear grinding machine in which the dressing mechanism is moved from .an1inoperative .-position to an operative position prior to I dressing and is adapted to be returned to inop'erat'rve-npo-i sition agaimaften dressing. and .in which, a safety device is provided.toLinsureQthatlTthei"dressin mechanismisininoperative pds'itionbefore grind- :ing'can-berestarted.

ustill anotherlbbject bilthelinveiitionj to'providea: dressing mechanism in'. Whi'blf the 'sidearid tip dressers are .moved .at. a'- fast, .rate .for roughdressing-and .at.a .relativ'ely. 'slowlrate for finish- .d-ressing anddn .whiehithe. rate .offm'ovement of the. dressers is controlled autom'aticallyby" the dressing. mechanism itself. in'fits operation. I

-Aiurthenobject .of..'.the invention is to provide a. gear grinding machine in which" thefigriniiing v wheel .isadvanced automatically between roughdressing .andifinish-dressingi sol as .to'fdetermine precisely the amount of stock' thatis taken'o'flth wheelin theilnish. dressing operation. -.A still further object of'th'inventiontistopro- U wide. ariressingmechanism which car'rbe adjusted readily for dressingwh'eelsj Jof various'i'diameters, heights, pressure angles; and: profileshapes.

Other. objects of 'the inventi'omwillfbe" appar- L entihereinafter from the specification-and from l the recital of'the appendedl'cl'aims.

..In the drawings: v w 1 i Fig. 1 is. an elevational' view looking at the wheel end of a spiral'bevehand hypoid'geangrinding machine, constructedaccoiding to-=the Wildhabef Patent 'Nof.2,252,743 and' providedwith the dressing mechanism" andiither"improvements"of the present invention;

(Fig; 2.is a fragmentary section'allview'approximately. onlthe line' 2 2 ofFigl 1,.sh'owing the*way in which. the banjo-type bracket is"m'ounted"'on 'themachine and showing part of the dressersli'de; 'Fie'l 3 is an 'elevational'view 'of'the parts shown in'Fig. '2 with "the whe'elguard inplace cert'ain of the parts being broken away; i

Fig. 4 is a fragmentary 'sectional'viewonan enlarged scale showing thevalvewhicmdetermines 'the' speed of movement of' the dresser slide and part-of the trip mechanism"'f0r' s'aid valve;

Fig. 1 5 is a" fragmentary= viewi'on an' 'enlarged sc'aleshowing part of the mechanisr'n ion-tripping thewh'e'el guard shutter;

Fig. 6 is a fragmentary view,'partly:imseotion,

showing thevpistonrfor actuating'theidressers. and the.mounting ofthis piston;

1 Fi 7-.- isa.=.--sectionalview: on the..1ine ll. of Fig.6;

- Fig. 8is a sectiononth'line' 8-.-8 of Fig. 6;

FiguQ-isa plan .view oice'rtain ofltheparts- .-shown. in Fig. 6;

'10 isa. sectional .view"through"the""side .'.dresser' block taken"substantia lly on"'-"thef*line I -40 of Fig. 6 and illustrating the operating mechanism for the side dresser arms;

Fig. 11 is a view through thi block taken substantially on the line ll|| of Fig. 6 and illustrating the means for locking this block in any position of its angular adjustment;

Fig. 12 is a section through this block on the line l2--l2 of Fig. 6 and showing the means for iadjus'tingthis block angula'rly; 13 is a fragmentary end view of the block, which is adjustable for control of the profile shape to be dressed on the grinding wheel of the 'dresser slide and of the banjo; Fig? 14 is an enlarged view, showin the detent bflfiidomrelea'sabl tzhoiding the dresser slide in inopeerative'pfl'sition during grinding;

Fig=15-is-a *fragmentary sectional view on an enlargedscaleoi part of the mechanism for operating the shutter on the wheel guard;

'Rigsiflfi to 19 inclusive are diagrammatic views showing successive positions of the. dresser. tools inlthe' operation ofLdressing a. grinding wheel with the, dressing mechanism of the-present invention; and

T." Fig, 20 is a" diagrammatic view of the hydraulic "circuit employed .fonactu'ating the dressing mechanism, the.dresser slide, and the mechanism; for advancingthe g'rinding'wheel.

Only so'mu'ch .ofthe machin of the Wildhaber Patent 'No; 2,252,743. :is: shown as is necessary to anunderstanding of the present invention. .The

" parts shown" in the present" drawings; which have .beemillu'strated; in the patent, are. designated'by 'thesamenumerals as are employed in the patent :except'thatthatareincreasedby 500. i Thus, in "thepatent;"the"cradle orthe' ma'ehineis denoted at'3'lz'an'd thewvh'e'el spindle: at 22. In the present application;'these same part are'denoted'hy' 531 and 522; respectively.

The grinding WheelW,:which isused on the *'ma'ehine;is seoured'to the wheel spindle 522 (Fig. 2). *This "spindle 'is journaled' on suitable bear- "ings: one ofwhi'eh'is'shownat 525;in a sleeve 521. '*The"s 1'eeve521 is adapted 'to' be moved axially to 5"advancefihe-grinding wheel to compensate 'for "wear and 'for dressing," and 'to this end is mounted 'on"an'gi1l'arly spaced sets ofrollenbearings, of

which'twosets are denoted M53! and '532;respectively. The sleeve 52'! constitutes theinner race for these--bearings whilethe outer race is denoted ThemOl-ler bearings and their races are mount- --ed irr a: 'car'rier"528.' The carrier 528 ispivotally mounted-in the 'cradle' '531 of the machinegarid "the'cra'd-1eis oscillat'ablymounted on rollerbear- 'ingS-SE l 'in'the cradle'housing "552.

' "The structure and mounting of the carrierand 'of 'the cradle is'described-in' detail in the Wild- '--ha'be'r patent above mentioned. A plate "25,

.60 Whichissecurd'to'the cradle by screws 26, and

a platetl; which is secured in any suitable-man- -n'er to the'plate25,'-'serve to close the openings "-pjrovided 'inthe front of'the cradle 'for adjust- '-ment'--"of' thecarrier528' therein. A circular 'gib 5' 29, which issecured' tothe cradle housing 552 by-screwswfl; 'servesto limit axial forwardmove- "mentofthe-eradle inthe housing. 'A circular guard- 32,-'which'-seats 'ina'recess in the carrier "-528, serves to-protect' the"bearings 532 and53l against *water andgrit. A' cylindrical collar' '33 surroundsthis guard; and 'J'ournaled by means of rollerbearings 34 onthis collar is the cylindrical or bar'ijo portion'35 of a dresser-carrying bracket "36 7s Ihe--seal31, which surroundsthe guard 32 and which is secured to the banjo portion 35 of the bracket 36, by screws 38, serves to prevent entry of water or grit into the front end of the roller bearings 34. A seal member 39, which also surrounds banjo portion 35 of the bracket 36, serves to protect the bearings 34 at their war from water and grit. The seal 39 is secured to the carrier 528 by screws .(not shown) which also serve to secure the collar 33 to the carrier.

The banjo bracket 36 has an elongated arm at one side which is supported at its outer end by a roller 45 (Figs. 2 and 3) which is mounted on a stud 46 that is secured in a bracket 41. The roller 45 engages in an elongated slot 48 formed in the rear face of the bracket 36.

The bracket 41 is adjustably mounted on an arcuate plate 50 (Figs. 1 and 2) which is secured to the cradle housing 552 by screws I. The plate 50 is formed with an arcuate T-slot 52 which is concentric with the axis of the cradle 531. The plate also has a series of equi-spaced notches or openings 54 formed on its periphery. There is a spring pressed plunger 55 mounted in the bracket 41 to be engaged selectively with the notches 54 in the plate 50. The plunger may be manipulated by the knob 56 and is normally held in looking position by the spring 51. A T-bolt 58, which engages in the slot 52, serves with the plunger 55 to secure the bracket 41 in any adjusted position on the plate 50. The roller 45 slides in the slot 48 so that the bracket 41 supports the bracket 36 in any adjusted position of the carrier 528. The bracket 41 is adjusted on the plate 50 to permit positioning the dressing mechanism so that the dressers will operate at a point substantially opposite the point of grinding, as will appear hereinafter.

There are two parallel cylindrical bars 60 and 6| (Figs. 1 2 and 3) secured in the bracket 36. There is a slide 62 mounted to reciprocate on the bars 60 and 6|. This slide is formed with a cylindrical bearing portion 63 (Fig. 13) which engages the bar 60 and with an elongated cylindrical portion 64 (Figs. 1 and 3) that is bored at 65 to receive the bar 6!. The bore 65 has its two ends closed by stufling boxes 66 and 61 of standard construction so that it forms a fluid-tight cylinder. The bar 6I has an enlarged portion 68 formed Within the bore 65 and this portion constitutes a piston which .reciprocates in this cylinder. A suitable pressure fluid may be supplied at either side of the piston 68 to move the slide 62 rectilinearly' in either direction on the bracket 36.

In Fig. 3, the slide 62 is shown at the limit of its outward movement, that is, in its inoperative position, which is determined by the engagement of the cap portion of the stufiing box 66 with a pad or stop formed on the bracket 36. The extent of inward movement of the slide is adjustable in accordance with the diameter of the grinding wheel W to be dressed. For this purthe direction of movement of the slide is a block 85 (Figs. 1 and 13). The slide 62 is formed on its front face with a dove-tailed guide portion 86 (Figs. 9 and 6) which engagesin a complementary slot formed in the rear face of the block 85. There is a screw shaft 81 journaled in the.

' vided with graduations, as indicated at 90 in Fig. 13, to read against an index pointer 9I which is secured to the slide.

Journaled in the block 85 (Figs. 6 and 13) is a cylindrical post 95. The post 95 is adjustable angularly in the block 85. This adjustment is eifected by rotation of a worm shaft 96 which is rotatably mounted in the block 85 and to which is keyed a worm 91. The worm meshes with a wormwheel segment 98 which is secured to the post 95 within a slot 99 formed therein. Angupose, there is a cylindrical stop member 12 (Fig. I

3) adjustably mounted in a bore formed in the bearing portion 64 of the slide 62 parallel to the bore 65. This stop member 12 is adapted to engage a pad or lug 13 formed on the bracket 36. The stop member 12 can be adjusted by rotating a shaft 14 which threads into the stop member 12 and which is journaled in the bearing portion 64 of slide 62. A graduated dial 15 is keyed to the shaft 14 to permit of making this adjustment precisely.

Mounted on the slide 62 for rectilinear adjustment thereon in a direction at rightangles to lar adjustment of the post 95 in the block can be made precisely by use of the graduations I00 provided on the block 85 and the index pointer ml which is secured to one end of the post 95. After the adjustment has been made, the post is secured in adjusted position by rotating the screw I94 (Figs. 6 and 8) to tighten the clamping blocks I02 and I03 on the periphery of post 95. The screw threads into the block I03 and is formed with a shoulder that engages the clamping block I02. The clamping blocks are of conventional form and have rounded clamping faces to conform to the periphery of the post 95.

There is a block I (Fig. 6) secured by screws I06 to one end of the post 95. Mounted on the block I95 for angular adjustment thereon about an axis which is at right angles to the axis of the post 95 is a cylinder block I III. The cylinder block II 0 is provided with a bore in which the piston III reciprocates.

Angular adjustment of the cylinder block III] on the block I95 is about the axis at (Figs. 11 and 12). It may be effected by rotation of the shaft 290 which is journaled in the cylinder block II 0 and to which is keyed a bevel pinion 20I. This bevel pinion meshes with a bevel gear segment 202 which is fastened to the block I05.

'There is a scale 204 fastened to the block I05,

and an index pointer 296 (Fig. 6) is secured to the cylinder b'lock IIO to read against the scale to permit this angular adjustment to be precisely. For guiding the cylinder block in its adjustment, there is a tongue 201 (Fig. 6) formed on the cylinder block which engages in a T-slot 208 formed in the block I05. Tongue 201 and T-slot 295 are concentric with the axis :13. After the adjustment is made, the cylinder block IIO can be secured to the block I05 in adjusted position by tightening up on the tongue or gib 209 (Fig. 11) through manipulation of the bolts 2I0. This tongue or gib 209 is formed concentric with the axis a: and fits into the T-slot 2 (Fig. 6) formed in the block I95 which is also concentric with the axis x. The gib 299 is secured to the cylinder block IIO by screws 2I3 and is relieved adjacent both ends so that when the bolts 2I0 II 2 me'shes'with .a'gear segment- I I 4:.andthe rack '11 I3::meshes .withia geansegment I I5. wThe seg- =-ment I I4 :isintegral with a-.:shaft"I'I6rwhich is mjournaled-in theblock I I and-whicl'uhas -a'reduced :outer end: on which: is mounted. arm I I1 FigsJ land that carries the' dressing'tool H8 (Figs. Land .16 to. 19) forr dressingthe. outside surface Oof. the, grinding I wheel. .=The=.armr I I1 :has'a split-I-clamp portiona'which fits over the: re-

. duced outenend of the: shaft IIGaandWhich is itightened'on' .theishafti by a1bolt: II9. .Thetarm,

I I1- .is held against'axial :rnovement'relativet to pshaft I I6:by the :headed: screw-124-which threads ;:int03' the: shaft.

which is of. reducedidiameter. at' itsouter1 end. The. arm .IZI'IFigs. 1,: 10 and 16"to*'19),=-which The segment H5 is integralrwithua'. shaft I20 I carries the dresser I22 for dressing the inside sur- Hfa'ce' I' of the grinding wheel, :is'. secured; to this 7 reduced portion of the'sha'ft I20.

.The arm ':has

'asplit-clamp portion'whicl'f'fits over the reduced;

outer end ofithe shaft I 20and which' is-tightened onuthe shaftiby a 'bolt? I23. The arm I2|..is.

" held:against axialzmoyement relative to shaft I20 by the" headed screw! I25 which threads into the .shaft.

iThBlShEtftSi I I6 and I20." are disposed-substantially at right angles to the outside andzinside surfacesO and.I;respectively; of:the grinding wheel W to bedressed. The. arm' I2I is shaped accord- :ing tot'conven'tionalpractic so' that. at .a'mean pointtof swing-f the arm; the'adiamond I22-will engage" thefinside surface 'of the "wheel at I a 1 pointflyingfin' the :same radial :plane :bf' the wheel as. .the p'o'int' of 'engagement of the :diamond 'I I8 with the outside surface of the wheelrwhen the arm H1 is at a mean point of-its swing; :The

arms 1' and I2I areso 'shaped'ortbent;more- -.over,1andthe dressers I'IBand I22'are'so mounted: therein thatfthe diamonds wnr lie substantially atright' anglesito the side'surfaces'which -ea'ch is'to dress. I

the shafts II6 andf120.

' From the preceding: description itiisseen that as the piston I I I is reciprocated in one direction or :thezother; it will impart rotary'rmotion to This will cause the' dressing'tools I'IB'iandY I22'tobe swungacross thezoutsideandinside faces; respectively, of the grinding wheel to'-dress .these faces. The shafts H6 and I20 :may also be moved 'axiallysimul taneously with'theirrrotary motions. For this :purpose; contact members 13!] and I3I and-cams l32aand I33 areiprovided. .Thei'contact member -"I30 is secured in an enlarged portion of the shaft II6;opposite-the segment II4-and-engages the front; face of the control member- I32. The

contact member I3I is secured in an enlarged :portion of theshaft' I20 opposite the segment I I5 and: engagesthe rear faceof the control member I33. :Theshaft H6 is journaled atits rear "endsin the control member I32, andthe shaft. 120' -.member I33.

plunger I31. "justed by a'nut I39Which is threaded on'the rear 'end of'theflplunger an'dis held in'po'sition naszanso I azinterposed between .the nut I39; anduthe-rearfiace I of; rthes-sleeveeportiona of; control member. I32tto .apply. aifriction loadionshaft. II 6 to takemp the .-backlash=. in the :gear train: driving. said.- ;shaft. 5 r The cap: I4 Irservesi to. protect theg partseagainst :qgr-it and-water. -This' cap threads into the sleeve .member- I42. This sleeve'member isvmounted -inthe.--bore-l43xof:zithe cylindenblock IID-uand serveseasra bearing: forthe controlmemben I32. 10' .The :plunger I31. is: held against: rotation-"rela- 'tivetto, the. shaft II 6: by. .pin I44 which-engages winearslot that is formed in the head I36:of-.the pplunger I31vand that "extends 1 axially "-of the .shaft.

The contactimember I3I. is held-:invengage- -.ment withthe reariface ofithe control: member I 33-.by.: a :coil: spring I50. This? spring engages -at one'iendwith the bottomyof .the :hole- I5I that '11s counterbored .in the shaft' I20, .and at its other 'zovendwith the'enlarged head.- I52 on a plunger I53-which is-lmounted in thiSfhOlG. Thej:plunger I53ris held'ragainst rotation relative to thershaft -I20-by.-a :pin': I55-which-engagesin a slot formed in theplunger. I53 extendingzaxially of the shaft. 5 -;A-p1ate I 56 whichis secured in anysuitabletman- "her I to the bearing rmember I51 serves *tOrrhOld .the':p1unger I 53 and :spring "I 50. in assembled -,-position. The plate I 56 may be .lined'with: fric- ..tion .'material toiengage the.head I52*of.plunger ,30' I53-- and.-apply friction to'shaft' I20 -totake -up with a shaft I12=which is journaledin the cylin- ..:der block I I 0. v:There -is'- a -long-faced spurs-gear I13 keyed --toz1the shaft- I12-and this-spur; gear "=.-meshes -with= a -spurgear I14 -which isz integ-ral xwithr-aashaft I15; Theshaft I'15-is journaled in +a.bloclc I16 whichis adjustable rectilinearly with referencetoathe cylinder :block H0 in a direction' at right angles. to the --longitudinal@ axis. of

--the cylinder I I I. .Thisadjustment can.-be made .-by rotation r-of thewscrew shaft I I11 whichwis journaled'inithe'cylinder block HO -and which threads into: a. nut: I18 that is secured. in the block I16. The long face of gear I13gpermits :loftmeshwbetween gear I13-and gear I14 dnnany .pIosi-tionof .this adjustment. The adjustment X canebe :madeprecisely by. use 'of" the graduated ascale' I19-whichis fastened-to the-block I16: and

'the Vernier I80 whichis securedtothe cylinde 60 block H0. I

Keyed-.toIthe-shaft-I15at the end opposite that" whichcanries the: gear I 14r-is' a. beveLgear 485. "Thisbevel'gear .meshes-with= a bevel-gear .I86 which .is integral withra-shaft- I81. '-When -..the block" I 1.6"is .in the zero "position of. itsnad- .,justment, .ltheraxiseof the shaftI81 coincides flwithtthe-zax-is .1: (Figs. 111andu12) about which .the. cylmden'block' H0 .is adjustable. This axis is:.normal-to .the p1ane containing the-axes-of :naledat-its upper end in a bushing "I 90;which .215: secured in. a block'I88, andat *its lower end is journaled directly in the block l88. The'block .I88zis wsecured -.-to I .the block I16 I 1by-bolts a1 89.

.There. ais a z -plunger I9 I mounted 7'3, I bore formed in shaft I81. A coil spring I92, which is interposed between the head of the plunger and a shoulder formed in the bore of shaft I81,

serves to hold the head of the plunger against 2 a friction plate I93 to put a friction load on the shaft I81 and take up backlash in the train driving the same. The plate I93 is secured in any suitable manner to bushing I96.

Mounted on the lower end of the sleeve I81 is an arm I94 (Figs. 1, 6, 16 to 19 inclusive) which carries the dresser I95 for dressing the rounds on the grinding wheel at the junctures of the sides and tip of the wheel. The arm I94 is formed with a split clamp at its upper end to engage over the reduced portion of the shaft I81 and is secured to the shaft by tightening up this clamp by manipulation of the bolt I96 (Fig. 6). A headed screw I91, which threads into the lower end of shaft I81, serves to retain the arm I94 in position on the shaft.

The arm I94 is of such length and is so shaped and the dresser I95 is so mounted therein that the point of the dresser I95 will travel in the radial plane of the wheel which contains the points of engagement of the dressers H8 and I22 with the wheel at mean points of swing of the arms H1 and I2I. To avoid interference between the dressers, then, the dresser II8 must travel from the base to the tip of the wheel while the dresser I22 is traveling from the tip to the base of the wheel and the dresser I95 istraveling from the outside to the inside of the wheel, as shown in Figs. 16 to 18 and as will be described more fully hereinafter.

The movements of the cylinder 64, which carries the dressing mechanism to and from operative position, and of the piston III which actuates the dressers, are controlled by a manually operable valve 2I5 (Figs. 1 and 20). This valve is reciprocable in a valve block 2I6 that is secured to the cradle housing 552. This valve also controls the operation of a piston 22!] (Fig. 20) which actuates the mechanism for advancing the grinding wheel axially between rough-dressing and finish-dressing to control the operative position of the wheel and the amount of stock taken off the wheel in the dressing operation.

In the machine of the,Wildhaber Patent No. 2,252,743, above mentioned, the advance of the wheel is efiected manually through rotation of the shafts 66, 63 and 68 shown in Figs. 3 and 4 of that patent. The last named shaft has a pinion 69 keyed to it which meshes with a pinion that in turn meshes with a pinion H on a screw shaft 12 to move the grinding wheel axially. In a machine constructed according to the present invention, the manual means for rotating the screw shaft may be replaced by automatic means. Thus the piston 220 of Fig. of the present application may replace the shafts 60, 63 and 68 of the Wildhaber patent. The piston 226 is provided with rack teeth 22I which mesh with the teeth of a gear 222 which may replace the pinion 69 of the Wildhaber patent. This pinion 222 may drive the pinion 10 of the Wildhaber Patent No. 2,252,743 through a pawl and ratchet wheel or other suitable form of oneway clutch so as to transmit motion to the pinion 16 on reciprocation of the piston 220 in one direction only.

The motive fluid is supplied to the valve 2I5 under pressure from the duct 225, and it is exhausted from the valve through the duct 226. This latter duct is connected to the valve through the four ducts 221, 228, 229, and 230. The valve has six spacing or guide collars formed on its periphery to closely engage the inside of the cylindrical bore 23I in which the valve slides. These spacing collars are denoted at 233, 234, 235, 236, and 238, respectively. The valve is turned to have peripheral grooves between these spacing collars in the usual manner. The valve has three parallel ducts 240, 24I, and 242, respectively, cut diametrically through it. These ducts communicate with a central duct 244 .that extends axially longitudinally of the valve.

In the position of the valve shown in Fig. 20, the pressure fluid flows through the duct 225 into the duct 24I and thence through the duct 244 into a duct 245 which communicates with a duct 246 that is drilled in the banjo bracket 36. This duct 246 in turn communicates with a duct 241 which is drilled in the bar 6I. Thelast named duct opens into the cylinder 65 at one side of the piston 68. At this same time, the opposite side of the piston 68 is on exhaust through the duct 250 in the bar 6 I, the duct 25.] in the bracket 36, the duct 252 in the bracket 36, the duct 253 which communicates therewith, andthe ducts 229 and 226 in the valve block 2I6. Thus, the cylinder block 64 and dresser carrying slide 62 are held in withdrawn position with the dressing mechanism in inoperative position.

At this same time, the pressure fluid flows from the duct 225 through the-ducts 24I and 244 of valve 2I5 into the duct 255 of thev valve block 2I6. The duct 255 is connected with a duct 256 through a ball check valve 251, but thepressure of the fluid in the duct 255 forces this check valve open so that the fluid may. flow into the duct 256. This duct communicates with the upper end of the cylinder I09 in which the piston III is mounted. Thus, at this time, the piston III is held down at the lowest position of its travel in the cylinder I69. The lower end of the cylinder is at this time on exhaust through the duct 258 and duct 259. The latter duct communicates with aduct 269 in the valve block 2I6, but the communication between the ducts 259 and 266 is closed by the pressure of the exhaust fluid on the ball check valve 26I. The exhaust fluid flows, therefore, from the duct 259 into another duct 262 which also communicates with they duct 259. The duct 262 communicates with a duct 263 through an adjustable needle valve 264 which threads into the valve block 2l6. The

duct 263 communicates, in the shown position of the valve 2I5 with the exhaust duct 221 which connects with the duct 226 leading to the sump of the machine. As .willbe obvious, adjustment of the needle valve 264 controls the rate of exhaust from the lower end of cylinder I69.

At this same time, also, the pressure fluid flows from the duct 255 into a duct 265 that connects with one end of the cylinder 224 in which the piston 226 is mounted. This holds the piston 226 at one end of its travel. The opposite end of the cylinder 224 is on exhaust through the duct 266 which communicates with two ducts 268 and 263-formed in the valve block 2 I6. The'duct 268 communicates with the duct 263, but in the shown position of valve 2I5 the connections between the two ducts is closed by pressure of the exhaust fluid on the ball check valve 210. The duct 269 communicates with a duct 21I, and the ball check valve 212, which normally tends to close the connection between these two' ducts, is at this time opened by the pressure of the exhaust fluid. The duct 211 communicates with the duct 263 which, in turn, communicates with the duct 221 that is connected to the duct 226 that leads to the sump.

To move'the slide 62 with the dressing mechanism into operative position,- when it 'is' desired to dress the grinding wheel W, the operator moves the valve 2I5 outwardly by pulling the knob 215 outwardly far enough for the-spacing shoulders 231 and 238 to be just above the ducts 253-and 245, respectively, and for the spacing shoulders 233 and 234 to be just below'the ducts 263 and 255, respectively. This will bring the spacing shoulder 235 about midway between :the ducts 225 and 228 and the spacing shoulder 236 about midway between the ducts 225 and 229. This causes the direction of fiowof the motive-fluid to be reversed between the opposite sides of the piston 68 Without altering the direction of flow of the motive fluid either to the piston II I or to the piston 220. The line-253 is put on supply and .the line 245 on exhaust, but the lines 256 and 265 remain on supply and the lines 258 and 266 on exhaust.- The supply to the line 253 is from the main pressure line 225 .through the ducts 24I and. 24 4 in the valve- 2I5, while theexhaust from the line 245 is through the duct 230 into the duct 226. that leads back to the sump. With the line 253 on pressure, the motive fluid flows through the ducts 253, 25I, and 250 to the right hand side of the piston 68. Thus, the cylinder block 64 and slide 62 are moved to'the right, causing the dressing mechanism to be moved into operative position. I

There is a rod 280 (Figs. 2, 3, 4 and mounted in the slide 62. This rod has an enlarged'head 28I which is adapted to engage with the-central prong 282 of a three-pronged wheel 283 as the slide 62 movesback and-forth in-its reciprocation. The wheel 283 is pivotally. mounted at 284 on a plate 285 which is fastened to the banjo bracket 36. There are two plungers 281 and 288 mounted in the bracket 36. These plungers are normally forced forwardly by springs 289 and-,290, but are pushed rearwardly against the'resistance of the springs on rotation of the wheel 283 in opposite directions. ancing medium, but the plunger 281 acts as a valve to control the connection between the duct I-and the ducts 252 and 294'. The last named duct communicates with the ducts 258 and- 259.

When the slide 62 moves from withdrawn position shown inFig. 3' to operative position shown in Fig. 2, the head 28I of the rod 280 moves from the full line position shown in Fig. 20- to the dotted line position shown in that figure. In this movement, the head 284 of the: rod engages the prong282 of wheel 283,.rocking the wheel about its axis and causing thexprong. 292 to depress. the plunger 288 against. the resistance of the spring 290. Nothing happens. however,

The. plunger 288 acts simply as a balbecause the plunger 288 is. simpl'ya balancing plunger.

In this same movement of the, slide 62 to operative position, though, the shutter in the guard for the grinding wheelis, tripped open so. that when the dressing mechanism arrives in operative position it will have access to the wheel. The wheel is enclosed by a guard 300. (Fig. 3) which is secured to the plate 31 (Fig-2) by screws 30I. The guard has an. opening in it at 304 to permit the grinding wheel. to engage in the toothspace of the gear being ground. 'Iiheguard also has an opening in it at 305 which is closed by the shutter 306 when grinding. is takingplace. The shutter 306 is mounted on an arm 30'! (Figs. 3 and 15). Arm 301 is keyed to a shaft 308' which is loumaled in'the banjo bracket '36.

The arm is rocked by movement of the slide 62. For this purpose, there is a lug 3I0 (Figs. 3 and 5) secured to the slide 62. Thislug is adapted to engage a roller 3 which is carried on a lever 3| 2 that is pivotally mounted by means of the stud 3I3 on the bracket 36. The end 314 of the lever engages in a slot 3 I 5 which is formed in a rod 3I6. This rod is slidably mounted in the bracket 36 and is provided at its forward end with rack teeth 3I1 (Fig. 15) that mesh with the teeth of a spiral pinion 3I8 which is keyed to the rocker shaft 308.

The rod 3I6 is normally held in its rightward position by a coil spring .3I9. This spring surrounds the rod and is interposed between. the collar 320 formed on the rod and the cap 32I which closes the opening in the bore of the bracket 36 in which the rod is mounted. As the slide 62 moves inwardly to operative position, the

.lug 3I0 engages the roller 3| I, causing the lever 3I2 to move the rod 3I6 to the left against resistance of the spring 3| 9 with the result that the rack 3I1 rocks the pinion 3I8 and the shaft 308 to open the shutter 306 in guard 303, and allow access of the dressing mechanism to, the wheel W.

The slide 62 moves to the right until the adjustable stop 12 (Figs. 1 and 3) contacts the lug or pad 13. The shutter 306 is then opened and the dressing mechanism is then in dressing position ready for dressing. The operator then moves the valve 2I5 (Fig. 20) further outwardly until the spacing shoulders 233 and 234 are above the ducts 263 and 255, respectively, and the spacing shoulders 235, 236, 231 and 238 lie just below the ducts 228, 225, 229 and 2 53, respectively. This causes the duct 263 to be put on supply and the duct 255 to be put on exhaust, while maintaining the ducts 253 and 245 on supply and exhaust, respectively. Thus the dressing mechanism is maintained in operative position while the piston III is moved upwardly in its cylinder I09.

The supply to the line 263, at this stage, is from the main pressure duct 225 through the ducts 24I, 244 and 234 of the valve 2I5, while the exhaust from the line 255 is through the ducts 228 and 226. With the duct 263' on supply, the ball check valves 26I and 210 are forced openand the pressure fluid flows into the ducts 259 and 266. From the duct 259, the fluid flows through the duct 258 to the lower end of the cylinder I09, while from the duct 266 the pressure fluid flows into the left hand end of cylinder 224, forcing the piston 220 to the right to advance the grinding wheel axially. The upper end of the cylinder I09 is on exhaust at this time through the duct 256, the duct 325, the now-open ball check valve 326, and the ducts 321, 265, 255, 228, 226, while theright hand end of cylinder 224 is simultaneously on exhaust through the ducts 265, 255, 228 and 226.

As the piston III moves upwardly in the cylinder block I09, the shafts II6, I20 and I12 (Figs. 7, 10, and 20) are rotated to swing the side and round dressers II8, I22 and I in one direction, respectively, across the outside, the inside and tip surfaces, respectively, of the grindingwheel'. In the swinging movement, the outside dressing tool I I8 moves outwardly from the position shown in Fig. 16 to that shown in Fig. 17, its tip swinging in the plane 330 tangent to the outside surface 0 of the wheel. In this swinging movement,

the inside dressing tool I22 moves inwardly from the position shown in Fig. 16 to the position shown in Fig. 17, its tip traveling in the plane 33! tangent to the inside surface of the wheel. In this swinging movement, the dressing tool I95 for the rounds moves across the tip of the wheel from outside to inside from the position shown in Fig. 16 to that shown in Fig. 1'7, its point tracing the are 332 around the tip surface of the wheel. Since the line 256 is open full to exhaust through the now open check valve 326 (Fig. 20), the described movement of the dressing tools is at a relatively rapid rate and they rough-dress the wheel.

,The movement of the piston 22!] to the right causes, as already stated, the grinding wheel to be advanced axially. This advancing movement brings the wheel into correct grinding position and permits of dressing the required amount on" the wheel. It will be noted from Fig. 17 that the wheel has been advanced axially from the position shown in Fig. 16 so that the dresser I95 dresses a round tipsurface on the wheel, removing the original flat at the tip.

The operator now reverses the movement of the control valve 2 I 5, moving the valve back to its intermediate position where the spacing shoulders 233 and 234 lie just below the ducts 263 and 255, respectively, and the spacing shoulders 231 and 238 lie just above the ducts 253 and 245, re-

spectively, and the spacing shoulder 235 is midway between the ducts 228 and 225 while the spacing shoulder 236 is midway between the ducts 225 and 229. This leaves the line 253 on pressure and the line 245 on exhaust, causing the I dressing mechanism to be held in operative position. It, however, reverses the direction of flow of the motive fluid to the cylinder I09, putting the line 255 on supply from the main pressure line 225through the ducts 24I, 244 and 234, the duct 255 and'the now open ball check valve 251. This causes the piston III to be moved downwardly in the cylinder I99 back to the position shown in Figs. 6 and 20.

This downward movement of piston II I causes the dresser arms II'I, I2I and I94 to be swung in the reverse direction from their previous movement. Hence the dresser II8 swings back in the plane 330 from the position shown in Fig. 17 to that shown in Fig. 18. Likewise, the dresser I22 swings back in the plane 33I and the dresser I95 swings back from the inside to the outside of the wheel to assume the positions shown in Fig. 18. The positions'shown in Fig. 18 are the same as those shown in Fig. 16. In other words, the

dressers return in the downward movement of piston I II to initial positions.

During this downward movement of piston I I I, the motive fluid exhausts from the lower end of the cylinder I09 through the lines 258 and 259, but the ball check valve 26I is closed by the pressure of the exhausting fluid so that the fluid can only flow back to the sump through the needle valve 264 and the lines 253, 221 and 226. Hence, the flow of the exhaust fluid is throttled so that the piston III moves downwardly at a reduced rate of speed as compared with its upward move-' tion shown in Fig. 20. This leaves the line 256' still on supply andthe line 258 still on exhaust, as shown, but it puts the line 245 on supply and the line 253 on exhaust, supply to the line 245 being from the main pressurev line 225 through the ducts 24I, 244 and 242, and exhaust from the line 253 being through the ducts 229 and 226 back to the sump.

This causes the slide 62 to be moved to the left from the position shown in Figs. 1 and 2 to the position shown in Figs. 3 and 20, thus withdrawing the dressing mechanism from operative position. As the slide 62 moves to the left, the head 28I of the rod 280 (Figs. 2 and 4) engages the spoke 282 of wheel 283, causing the plunger 28'! to be momentarily depressed against the resistance of the spring 289. This shuts off momentarily the flow of the exhaust fluid from the line 25I through the line 252 and causes thisexhaust fluid to flow momentarily instead from the line 25I into the line 294, whence it flows I into the line 259. The pressure of the exhaust fluid then momentarily closes the ball check valve 261 so that the fluid must travel through the .needle valve 264 tothe lines 263, 227 and 226 to Y the sump. Thus, momentarily, the withdrawal movement of the slide 62 is slowed down. It is at this moment that the dressing tool 335-(Fig. 19), which is mounted in the same arm I2I that carries the inside dresser I2 2,'passes across the tip of the wheel in the withdrawalmovement-of slide 62. Thus the dresser 335 is caused to dress a straight profile on the tip of the wheel by the movement of slide 62.

because of the retardation of the slide movement during the dressing.

The dresser 335 passes, of course, across the tip of the wheel in the movement of the slide to operative position as well as in the described movement to inoperative position but since the wheel is not advanced until after the dressingmechanism is in operative position, the dresser 335 does little or no dressing in the movement of the slide to operative position. 3

The dressing tool 335 is shown in Fi 19 at a point in its travel just after it has completed its dressing movement. The other dressing tools I I8,

I and I22 are shown in this figure well to the left of the tool 335, as they would be at this stage of the withdrawal movement ofthe slide I32.

As soon as'the head 28I of the rod 289 (Figs. 2, 4 and 20) has cleared the-spoke-282 of wheel 283, the valve 28'! pops back into the-position shown under actuation of the spring 289. Thus, the line 294 is again shut off while the line 252' is again connected to the line 25I to conduct the exhaust fluid from the right hand end of the piston 68. 'Hence, the slide 62 resumes its rapid 'movement to inoperative position.

During this withdrawal movement, the lug 3IIl (Figs. 3 and 5) moves away from the roller 3II and'the spring 3l9 serves to return the rod 3l6 to its leftward position causing the shutter 306.

circuit of the motor (not shown) whicnoperates the machine during grinding; .It'is a normally open switch and must be closed to maintain the The tip surface dressedon the'wheel by this movement is finish-dressed circuit to said motor. 1 The switchisiclosedpwhem theissl-idei 62 1 is returned ltoxinoperativex 2 position; bysengagem'ent ofthe contaet:.rlug.z 338; which: is formed I OILuthenSlide 62, with: lthez lu'nger: 1338:;

Thisr'plunger slides in a hole provided in the'lorackez- A et :36 iandriengages the. arm .of the limit: wswitch. It will be seen,rthen', thatrwhen the dressing3mech-a 4 anism is moved to operativesposition thexcons. tact lug 338 :willmbelcarried; away fromilplunger 339 to.;allow .theilimitswitcha33l Ito copen;z..stop;-

ping ltheemain'xdrive motor of theumachinep and that thisxmotor cannot berestarted'imtilthe:slide 62 is back-in inoperative.position-again.. Thus the "limit switch; 331; acts as. aisafety device ,ine

suringthat the dressingmechanism is; out of the: 15,;

way .:before :the grinding: operatiomcan beestantedz' Aszshown in l, the :s1idea62,whemitpisin; withdrawn position; is :inclined tmthehorizontal and therefore wouldlitendiunder actionrof gravity I to slide down 'to- Operative position; To'iprevent ,20 this, a stop-is provided to ,holdc the slide frictione ally; in inoperative positiom. This stop is {shownin Figs; 3 and 114;: Theistop; includes-eav pin; 34 0" which screwscinto the slide 6 2- .-and. projects from the backthereof. The rearwardlysprojegcting;end.

ofpthisapins isof substantially, \L-shape; It is adapted to engagelthe .substantiallyy -'shaped for: wardly projecting, end of a plunger 5 3 :Which is mounted:withinasleeve'unember 342- thatiisn; securedainthe bracket136. Thecplunger 3 :is normallypressed. forwardlyby filCOil ispring, 343 which is interposed betweeneanuenlarged .flange. 346 formed. on the plungenand asnut .344 :that. threads into the sleeve 342. Atpinl 345 which is, secured in: the; sleeve i342 and: engages ills-a hole in the flange. r 346 serves,- to hold theaplungeh against rotation. The pressurerofilthe;spring;.343

is normally enough vtohold. the slide 52in inoperative position; but when .there is-hydraulicpressure onlthe piston 68-to ,move the slide to;;oper- 40.

ative position, theplunger :3 willibel depressed against the, action ofthe spring; Likewise;.,onr return movement of theslide, theplungerfl34l" will again be depressed to,allow,the-.-slide,-, 62 to return to inoperative position.

The operation of the dressing mechanism 3 of the, present. invention, will be,- understood from, the preceding, description butmay, briefly, be summed up here The various parts of the mech-,.

anism are, 1 of course, first. adjusted in accordance .150 I to dress on the wheel Iflituisrdesiredlto dress an approximately. straight profile-1 on the. wheel, the block is so.adjusted that the sideedressers I I8 and.I22 iwilliswing about axeswhichiareperpendicular to planestangenttothta .sidesof the wheel. at the points of'contact oflthedressersww with ..the.,wheel. A Lconcave or a convex profile may beldressed. on,.the.- wheel by adjusting -,the

blockl85so that .thedresser axes. areabove or below this mean position, respectively. By ad: justment. oftthelpost in the 1block. 85, th'epo- 70 sitionof swingrof. the'.axes. of lthelside dresser, arms can be further changed so ,asefunth'er, to. control the'profile. curvature dressedlonthe wheels All? this in .accordance with .the principles of It. limits .the .in-- 55 Adjustment of (the zcylinderr block: I Idwonw the 1. blocki I 051 (Figs. 6)] permits of :1 positioningzl the s. dressings tools; in accordance-. witln the zpres sureziangles: of the s insider.- ando outside sur-ifacesswhich it is desired--fto. .dressi=om the wheel; Adjustment of 'the-b1ock'tt16 :(Figss 6 and 17) :on: the cylinder. block I I0 permits ofrrsetting-the axis of :swing'of theround dressingtool I95 in accord ancezzwithi the *locationn desired for the rounds. The .axis of "swing :of theround dressing toolimay be symmetrical-of the sides ofithe 'wheel or un symmetrical thereof. inaccordance with-the shape whichsit is desired; to'dressv Adjustment of the= bani orbraoket 3B 'angula'rly on:the:'p1ate-5Il' '(1"ig".

2) permitsnof avoidhaganyvpossibillty '01: inter-- ferenceiofthe dressingr'mechanlsm withthe work' regardless. iofn the position which" the wheel" oc-- i cupies" about the axis: :of the cradl'e because of i the spiral angleadjustment ofcarrier" 528,- This is done *by releasingzthe T-bolt '58 )andnkeeper-SI (Fig. 2) and moving .the banjo:SIiitO-"the'desired positiongthen allowingthekeeper to engage again with: one of' the" notches: '54 in the arm 50 and I tighteningmp :the T-bolt' 58. The' throttle valve 264" (Fig; 20) is also adjustedinaccordance with the desired :speed .of movement of athe 'sdressing tools in; finisht-dressing; that is; in accordance": with the finish which it is desired to dress. on the wheel; For dressing the sides of thelwli'eelsato profile shapes: ofv 'varyingzinclinationrto the-wheel axis, controlmembers 1 32 :and :1 33 (Fig.1: 10) will 2 be used? which-jlwilli, produce the-:required': axial; movementsiof the side dressers during-swing? of the dresser. armsil I! ,and: I 2 I-.. Ifrno axial moves.

ing, then flat-surfaced; discs will. be lusedaafort' the control 7 members, that ,is ldiscs having; .con-:. tact surfaces normal to ,the axeszof; shapes I I3 and I I6.

When all of thezadjustments have been made; the dressing mechanism iS:;readf01'-1 operation-.1v When the operator: desires' to'r dress the wheel, then,:he moves the valve 2 I 5 outwardly-.toits first: position; putting the.;lines 253; 25I' and 1250 (Fig;-v 20) on supply :andzthe lines 241 and .245 -on eex-s haust; causing the ,cylindepblock; ISA-with the slider; 62 to be moved tothe right to carry-the-dressing' mechanismto operativeposition; At the-very be-: ginning .ofthis --movement,..the; contact member 338 moves away. from plunger 339, allowing; the a limit switch 1331 to open; stopping the :main,clrive'a' motor ofthe machine; In thismovement, also,:as previously described, the head 28I of-the pin 28Il will ratchet idly over the .wheel 283,i(Fig-, 2) and. the shutter;3ll6 &inthe dresser guard :(Fig; 3) will be opened by engagement of the'lug 3I0 with rolle133 ;(Figs. 3 and .5). Thenv the operator moves, the valve 2 I 5;to its uppermost position which'putsx, the .line. 2 58 and. 266- to the cylinders :I 09 and--.22l, respectively, on'supply and the lines, 255 and 265- fromthese cylinders, V respectively,- ,on exhaust A while keepinglthe lines 253,-;25I and 250'on's11DD1y and the lines 241,248 .and245 on exhaust Thus; while the-1 dressing mechanism is ,held in opera- ,tive position, the wheel ,is-:advanced.axially and. thepiston III .is moved upwardly-in its ,cylinderl I09 .to rotateathe arms Ill, I2I and-:IMIFigs. 1- and.-,16) to cause the outside, ,insideiandround, dressing tools. I I8,-- I22, and I 95 to. dressrthellwheelrr ;In this dressing operation, the dressers are swung, from the positions shown. in 16 ,to .the. positions showninlFig. 17.. Since the ,line256 is at. this :time freely open toexhaust thr'oughtheduct x 325, "th'e opencheckfvalve325; andthe ducts-321:

theQWiIdhaber and Carls'en Patent lio..2;311;3 02'.i ;255,,' 228 land 225 thev dressingl' operatlon takes place at relatively high speed, rough-dressing the wheel. Then the operator moves the valve'2I5 downwardly again to its intermediate position, putting the line 256 of cylinder I09 on supply and the line 258 on exhaust while keeping the lines 253, 25I and 25!] of cylinder 65 on supply and the lines 24?, 246 and 245 on exhaust. Thus, while the dressing mechanism is retained in dressing position, the piston I I I is moved downwardly in its cylinder to swing the outside, inside and round dressing tools II8, I22, and I95, respectively, from the positions shown in Fig. 17 to the positions shown in Fig. 18 which is the identical position with those shown in Fig. 16. Since, during this downward movement of the piston II I, the exhaust from the lower end of the cylinder I09 through the lines 258 and 259 is throttled by the needle valve 264 the rate of travel of the dressing tools from the positions shown in Fig. 17 to those shown in Fig. 18 will be relatively slow and the wheel will be finish-dressed. The operator then pushes the valve 2I5 further down to its lowermost position. This keeps the line 256 on supply and the line 258 on exhaust, holding the piston III at the lowermost position of its travel in its cylinder, but it puts the lines 245, 246, and 241 on supply and the lines 250, 25I, and 253 on exhaust, causing the slide 62 to be moved to the left toward inoperative position. At the very beginning of this movement, the head 28I of the rod 280 rides over the prong 282 of the wheel 283, depressing momentarily the valve 28'! (Figs. 3, 4 and 20). This causes the fluid from the right hand end of the piston 63 to flow momentarily from the line I through the lines 294 and 259 and throttle valve 264 to the sump, so that momentarily the withdrawal movement of the slide 62 is slowed up. It is at this time that the dressing tool 335 (Fig. 19) carried by the inside dressing arm I2I passes across the tip T of the grinding wheel, dressing the wheel along the line 336. As soon as the dressing tool 335 has cleared the wheel, the head 28I of the pin 280 will clear the pron 282 of the wheel 283 and the valve 281 will be released to spring back to its normal position under actuation of the spring 289, connecting the line 25I again with the line 252 for normal exhaust from the right hand end of the cylinder 54. Thus the slide 62 with the dressin mechanism is moved on at high speed to full withdrawn position. During this withdrawal movement, the lug 3H1 (Figs. 3 and 5) will clear the roller 3I I, allowing the shutter 396 of guard 300 to be closed under operation of spring 3L9. At this same time, the pressure fluid in the line 265 will move the piston 220 back to the position shown in Fig. 20, resetting the wheel advancin mechanism. The operation of dressing will then have been completed. When the slide 62 reaches fully withdrawn position, the lug 338 (Fig. 3) engages plunger 339 to close limit switch 331 and the grinding operation of the machine may be restarted.

With the dressing mechanism of the present invention, it is possible to arrange the tubing, which connects the control valve 2I5 with the various fluid-pressure operated parts of the dressing mechanism, at one side of the machine as shown in Fig. 1 so that it can readily be guarded. This was not possible with previous designs of dressing mechanisms for bevel and hypoid gear nders where the dressing mechanism moved with the wheel in the spiral angle adjustment of the wheel because there the tubing had to extend across the face of the cradle. Moreover, with the present invention, the lengths of the tubing are shortened. With the new construction, the tubing only has to be long enough to reach bracket 36 when it is in its highest adjusted position on plate 50. With the prior design, the tubing had to belong enough to reach the dressing mechanism in any position of spiral angle adjustment of the wheel with the result that when the wheel and dressing mechanism were in an adjusted position close to the control valve, the tubing hung in long loops and folds which were hard to guard and detracted from the appearance of-the machine. Withthe new construction, moreover, the weight ofthe dressing mechanism is carried by the cradle housing through the bracket 41 and roller 45. The result is that the cradl can be oscillated at high speed and no unbalanced condition results from the mounting of the dressing" mechanism on the machine. In this respect, the machine of the-present invention is a distinct improvement over prior designs.

While the'invention has been described in connection with a dressing mechanism for dressing an annular wheel and in connection with its use on a particular type of grinding machine, it will Ibe understood that the dressing mechanism of this invention may be employed in dressing other types of wheels and on other types of machines. It will be further-understood that while the invention hasbeen'described in connectionv with a particular embodiment thereof, it is capable of various further modifications. The present application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within knownor customary practice'in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described-my invention, what I claimis:

1. In a machine for grinding gears in a generating operation, the combination with a cradle, a housing in which the cradle is oscillatably mounted, a carrier mounted on the cradle for angular adjustment about an axis offset from theaxis of the cradle, anda'grinding wheel journaled rotatably 'on said carrier with its axis oifset from" the axis of the carrier, of a bracket which is secured at one end to said carrier and at its opposite end to said housing, and mechanism for dressing the grinding wheel-mounted on said bracket.

2. In a machine for grinding gears in a generating operation, the combination with a cradle, a housing in which the cradle is oscillatably mounted, a carrier mounted on' the cradle for angular adjustment about an axis ofifset from the axis of the cradle, a spindle journaled in said carrier with its axis offset from the axis of the carrier, and agrinding wheel secured to that spindle, of aibracket which is secured'at one end to said carrier-and'at its opposite end to said housing, and a dressing mechanism slidably mounted on said bracket for movement to and irom operative relation with the grinding wheel.

' 3: In a machine for grindinggears't-he combination with a housing, a support adjustable angularly in'the housing, a rotary spindle, a grinding wheel secured thereto, and a carrier in which the spindle" is journaled, said carrier being mounted adjustably on the support to adjust the tancerof' the axis '.:of the: spindle: from .the: axis about-which the supportzis adziustable, of a) bracket which'is ournaledat onerendrcoaxiallmofzthe spindle, means adjustably-isecured: tdthehousing for adjustably. supportingthe oppositeendzofithe bracket, said meanstbeingeadiusthble: angularly on the housing about.theeaidsraabout whichsthe support? is adju'stablez' and :being adjustablei with reference to the bracket fradially not i the i' last named axis; :fluid=:pressure-.:operated mechanism mounted. on said bracket for1dressing:said z grinding "wheel, 1 and ::means 11 connected 2 170 the last namedrmeans and: mounted-r.onzsaidhousing tor controlling the operation sof saiddressingzmeans. ;5.:In azmachine foragmindingsgears' in eugencrating: operation; thercombinatiorrcwithza cradle, a housing on "which"; the xcrad'le :is oscillatably mounted; a: carriermounte'd orrthecradle for an- .guiarzadjustmentiaboutzan axiszo'flset fromvthe rieriwith cits .axiszoffset from the axis':0f'..the car- 'rier',.1andaa' grindingvwheel" securedzto zsaid spindie: of; arbraeket' which is: securedaat'ioneiend'to said'scarrienanchat its opposite :enditmsaid rhousing,.aanddressingtmechanismranountedomsaid bracket: for '..dressing;.saidagrinding" :wheel, K fluid pressure operated-means for actuatingsaid-dressing;mechanism;v a 'valve tmountedwom said housing for controlling the operation of the-"dressing mechanismmucts f-orconducting the motive fluid from said valveto saidibrackets, andiductsrinsaid bracket for communicating *with" the first: named ducts for conductingrt the motive fluid to the dressing mechanism.

6. Irr-a: grindingmachine; a'; support;..'a spindle joumaledi in? the "support;.:.a; gninding wheel secured to the spindle; a, carriage'mountedzon the support, :dressing mechanismmounted; on .the carriage and comprising .a pair of: dressing-tools, oneof which'is movably-mounted on-the carriage and the other of which is fixed relative thereto,

'means for-movingthecarriage ori the support to cause the second tool 1 to dress the wheels and-to move the first tool'to and from operative'relation withthe wheel; and means forimovingl .theifirst tool when-the carriage is: in' operative position to cause said tool to dress the-wheel.

- 7. Mechanism ior dressingaa a'otaryrgrinding :wheelcomprising a support; arpainofshaftsgiomnaled 'in said support with;.their. axes in -,a::ic,ommon plane but inclined rto one: anothenian' arm secured to each' of "said? shafts, dressing tools secured: to saidarms 1 in eposition to i-:d1-.ess: opposite sides" of a grinding: wheeh-irespectively; a: reciprocable"-' piston'ismounted between :tsaid sshfits, -m'eans' I operatively; connecting; .saidmi'stomtd I the two shafts to move the shaftsfin-oppos'rtedirections on movement of 'thevpiston; a' third: shaft operatively connected to: the piston tori-movemounted on thei support to wary: thei radi'aILLdiS- axis of; thecradle a spindle journaled ims'aidncarment about antaxis textendingaat':;tight-iang1es .75

amaeeo .to: the plane, oit-henaxes oithe other twodsheits, ca :drssingtool secured. to said last namedrshaft in zposition todress'the tip of the grinding wheel and rounds at the juncturespf, the tip with oppolsitersidesofithe wheeL; and means for applying fluid .pressure; selectively to opposite, sides of the piston to swing thedressing tools across the sides and .tip: of. the wheel.

- 8, Inca grinding machine,asupport, a, spindle journaled ,in thesupport, a; grinding Wheel secured to-thespindle; a-carriage movably mounted ronthesupport at one side ofv the wheel, a pluralitytofz arms reciprocablytmounted onthe carriage, idresserssmounted on two. of: said arms. for dressing opposite sides,- respectively, of the'wheel, :a dresser mountedon a thirdearm for dressing the tip of the whee1,.;means for-moving the carriage .toemove. the dressers,v from an inoperative position; clear pfwthe wheel to operative positiontto ..permit thecdressers to: engage the wheeh and means aior 1 reciprocating said arms to effect dressing, saidarms-being ISO mounted on said vcarriagethat the dresser, which dresses the side ,ofztherwheel-that isimore. remote from the carriage,;movesfrom the tip of tlie active portion ob saideside ofthe wheel to the base thereoiand .back-again iin a; cycle ofits reciprocation, while the .d ressenwhichidressesytheiside of the wheel that is:nearer the carriage,' moves from the base of" the; active ,portionof said side of the wheel :tothetip thereof@and,-bacl a ain in a cyclenof its reciprocartion, whilefthe dresser, which dresses .the tiprof -the whee1,,moves, from the sideof, the whe'ehnearer the. carriage to; the, side, of the wheel more-remote fromthecarriag and back again-in .-the cycle ,of its reciprocation.

: 9.11m a. grinding machine; a support, a. spindle -,io-urna1ed..;in the support, a-. grind,in wheel: secured tethe. spindle, a-garriage-mombly mounted on thesupport at, one. side-of the wheel, a plurality: of armsrreciprocably: mounted on the .carria e;.dressers mounted; on two of said arms ior dressing opposite sides, respective ly, of the'wheel, =a-zdresser mounted oil-1a thirdarm fordressing 'rounds at the 'j-unctu-res of. the sides .ot'the wheel "with its; tipasaid lastnamed arm ,being reciprocablecon the carriagei about a relativelmfixed iaxis, means, for-moving the carriage to movecthe ,dressersfrom, inoperatiyeposition clear-of the :wheel tooperative position topermit the dressers teengagethewheel, means for reciprocating said arms'to-effect dressing,- said arms being so mount.- ed "on said carriage. that .the dresser, which dresses theqside 0f. the wheel, that is more remotemfromrthe carriage, moves, from the tip, of thez active-r portion ofsaid side of the wheel to theibase. thereof and back again in a cycle of its reciprocation, while the dresser, whichdresses the .sideof the wheel that is nearer the carriage, moves from the base of the activeportion of said side of the wheel-to the tip thereof and back ragainuinpaflcycle of; its reciprocation, while the dresser which dresses the rounds on the. wheel, imoves acrossthe, tipof the wheel from the,;side ofJlthe wheel. nearer the "carriage, to. the side of the whe'eLmore remote from the carriage and back' again in a cycle of its reciprocation; and a fourth dresser mounted on-thesame arm with -the first'described dresser-in such position that, when said arm has completed the cycle of' lts movement, the fourth dresser is in position to he passedacross the tip of the wheel by the movement of Lthe'carriage itself to inoperativeposi- .tion.

110.: In' a'grinding machine,- asupportpatni dle joumaled-in the support, a, grinding wheel secured to the spindle, a carriage reciprocable on the support, a shaft journaled in said carriage, a pair of dressers mounted on said shaft to project therefrom at angles to one another,

means for rocking the shaft to move one of the dressers across a side of the wheel to dress the same, and means for moving the carriage to cause the other dresser to dress the tip of the wheel.

11. In a grinding machine, a support, a spin-' dle journaled in the support, a grinding wheel secured to the spindle, a guard for enclosing-the grinding wheel and comprising a fixed portion and a movable shutter, a carriage reciprocably mounted on the support, dressing mechanism mounted on the carriage, means for moving the carriage to move the dressing mechanism from inoperative position clear of the wheel to operative position to engage the wheel, and means responsive to the movement of the carriage to open the shutter on movement of the dressing mechanism to operative position and close the shutter on movement of the dressing mechanism to inoperative position.

12. In a grinding machine, a support, a spindle journaled in the support, a grinding wheel secured to the spindle, a carriage mounted on the support, dressing mechanism mounted on the carriage and comprising a pair of dressing tools, means for moving the carriage on the support to move the dressing mechanism to and from operative relation with the Wheel, means for moving one of the tools independently of the movement of the carriage to effect dressing movement of the tool, said other tool being so mounted as to dress the wheel by movement of the carriage itself, means for controlling the speed of the movement of the carriage,- and means operatively connecting the last named means to the carriage to actuate the last named means on movement of the carriage.

13. Mechanism for dressing a rotary grinding wheel comprising a support, a pair of dressing tools movably mounted on'said support, means for moving one of the tools in an arcuate path across the tip of the wheel from one side of the wheel to the other to dress an arcuate shape on the tip of the wheel with rounds connecting the sides with the tip, and means for subsequently moving the other dressing tool automatically in a straight path across the tip of the wheel to re-dress the tip of the wheel and form a straightprofiled tip thereon.

14. Mechanism for dressing a rotary grinding wheel comprising a support, a carriage movable on the support, a dressing tool fixedly secured to the carriage, a'second dressing tool movably mounted on the carriage, means for moving the second dressing tool in an arcuate path across the tip of the wheel from one side of the wheel to the other to dress an arcuate shape on the tip of the wheel with rounds connecting the sides with the tip, and means for subsequently moving the carriage to move the other dressing tool in a straight path across the tip of the wheel to dress a straight tip on the wheel.

15. In a machine for grinding gears, a support, a spindle journaled in said support, a grinding wheel secured to said spindle, a slide reciprocably mounted on the support for movement radially of the axis of the spindle, an adjustable stop for limiting movement of the slide radially toward the spindle, a block mounted on the slide for adjustment in a direction at right angles to the direction of movement of the slide, a carrier journaled in the block for angular adjustment about an axis extending in the direction of movement of the slide, a second block mounted on the carrier for angular adjustment about an axisextending at right angles to the axis of adjustment of the carrier, a dressing tool oscillatably mounted on the second .block and arranged to dress a side surface of the wheel, a second carrier adjustable on the second block in a direction parallel to the direction of movement of the'slide, a second dressing tool oscillatably mounted on said second carrier for swinging movement about an axis inclined to the axis of oscillation of the first dressing tool to dress the tip surface of the wheel and rounds joining the tip surface with the sides of the Wheel, and means for oscillating said dressing tools.

16. Mechanism for dressing a rotary grinding wheel comprising a support, a pair of shafts journaled in said support with their axes lying in the same plane but inclined to one another at'an angle equal to the included angle between opposite side surfaces of the wheel to be dressed,an arm secured to each of said shafts, a dressing tool secured to each of said arms in position to dress opposite sides of the Wheel, respectively, a third shaft journaled in said support with its axis parallel to the plane of the first shaft but offset therefrom, a fourth shaft operatively connected to the third shaft and having its axis at right angles to the axis of the third shaft, an arm secured to the fourth shaft, a dressing tool secured to said arm in position to move across the top surface of the wheel from one side thereof to the other on rotation of the fourth shaft, and means for oscillating said shafts comprising a piston mounted on said support between the first two shafts, a pair of racks secured to opposite sides of said piston, spur gears secured to each of the first two shafts and meshing with said racks, a third rack secured to the piston, a spur gear secured to the third shaft and meshing with the third rack, and means for applying fluid pressure selectively to opposite sides of the piston.

17. In a machine for grinding gears in a generating operation, a cradle, a housing on which the -cradle is oscillatably mounted, a carrier adjustable about the axis of the cradle, a grinding wheel journaled in thecarrier, a bracket secured at one end to the carrier for adjustment angularly thereon about the axis of the grinding wheel, a pin mounted on the housingfor adjustment about the axis of the cradle and adapted a. cylinder and a piston reciprocable therein, one

check valve mounted in one of said ducts to be opened when said duct is on supply to allow free flow ofthe pressure fluid through said duct but tube closed when said duct'isl on: exhaust, a third duct connected to the said duct to conduct the exhaust fluid therefrom when the check valve is closed, and an adjustable throttle valve in the third duct to govern, the rate of flow of the exhaust fluid through the third duct whereby to control the rate of movement of the: dressing tool in' one direction of its movement.

19. In a grinding machine, a support, a spin.- dle journaled in the support, a. grinding: wheel secured to the spindle, a carriage movably mounted. on the support, dressing mechanism movably mounted. on the carriage, fluid pressure operated means for reciprocating the carriage to movethe dressing mechanism to and from operative relation with the wheel, fluid pressure operated means for moving the dressing mecha-' nism, when it is in operative position to efiect the dressing operation, a single control valve for the two fluid pressure operated means, said valve being so constructed that on movement step-bystep in one direction the carriage is first moved to carry the dressing mechanism into operative position and then the dressing mechanism is.

moved in one direction across the surface. of the wheel to be dressed, and on movement of said valve in the opposite direction the dressing mech anism is first moved? in the opposite direction acrossthe surface of the wheel to be: dressed, and then. the: carriage is withdrawn to inoperative. position.

20. In a grinding machine, a support; a grinding. wheel journaled. on said support, a carriage reciprocable onsaid support, fluid pressure operated: means for reciprocating said carriage, a pair of dressing tools mounted onsaid carriage, one of which relatively fixed to the carriage in position to be operated by the movement of the carriageitself, and the other of which is mounted on the. carriage to be movable independently thereof; fluid pressure operatedmeans for recip:- rocating the second dresser, and a single throttle valve operatively connected to both said fluid pressure operated means for controlling the rate of movement in one direction of both fluid-pressure operated means whereby to control the rate of operation in one direction of. both dressers.

21. In a grinding" machine, a support, a spindle journaled in: the support, a grinding wheel secured to the spindle, a carriage mounted on; the support, a dressing mechanismmounted on the carriage comprising pair of dressing tools, one of which is movably mounted on the carriage and the other of which is secured to the carriage in fixed relation thereto, means for moving the first dressing tool back and forth across the wheel when it' is in operative position, to dress the wheel, means for advancing the wheel axially between the said movements of the first tool, and means for moving the carriage on the support to carry both tools to and from. operative. position and to cause the second tool to dress the wheel on movement of the carriage from operative position.

22. In a grinding machine, a support, a spindle journaled in thev support, a, rotary'annular grinding wheel secured to the spindle, a carriagemounted on the support for movement in a direction perpendicular to the axis of thewheel', dressing mechanism mounted on the carriage and comprising a pair of dressing tools, one of which is movably mounted on the carriage to dress a side of the wheel and the other of which is securedto the carriage-in fixed. relation theretotodress-the tip of: the. wheel, means for. moving thefirst: tool= back and forth across the wheel'when inoperative position, means. for advancing the wheel axially between the said movements of the first tool, and means for moving the carriage on the support to move both dressing tools to' and from operative position and to cause the second tool to dressv the wheel on movement of the carriagefrom operative position.

23. Ina grinding machine, a support, a spindle journaled in the support, a grinding wheel secured to the spindle, a carriage reciprocable on the support, a dressing tool fixedly secured totheeca-rriage in position to dress a surface of the wheel, a second dressing tool movabl'y mounted on. the carriage in position to dress a different surface of the wheel, means for moving thecarriage at high speed in opposite directions to move the tools to andfrom operative relation with thewheel, means for moving the second toolat a relatively fast speed in one direction and at. a relatively slow speed in the opposite direction, while in operativeposition, to cause it to roughdress and finish-dress a wheel surface successively, and. means for decelerating the speed of movement of the carriage during part of, its movement in one direction, while the first tool is dressing the wheel, to cause said first tool to finish-dress the wheel surface.

24. In a grinding machine, a support, a spindle journaled in the support, a grinding wheel secured to the spindle, a carriage reciprocable on. the support, a; dressing tool fixedly secured: to. the: carriage in position to dress a surface; ofthe" wheel, a second dressing tool movably mounted on the carriage in position to dress a different: surface of the Wheel, fluid-pressure operatedmeansfor moving the carriage in oppositedirections to move the tools to and from operative relation with the. wheel, fluid-pressure operated means for reciprocating the second dressing tool. to cause it to dress; the wheel, an adjustable throttle valve for governing the rate of return movement of the. second dressing tool so as to cause it to travel at a slower speed on its return movement than on its; forward movement, and; means operated by the carriage in its: return movement for operatively connecting the throttle valve to the fluid-pressure operated means for actuating the carriage, whereby the rate of. return movement of the carriage is decelerated duringthe time the first dressing tool is dress.- ing the wheel on the return movement of the carriage.

25. In a grinding machine, a support, a spindle journaled in the support, a grinding wheel secured to the spindle, a carriage movable onthe-support, a dressing tool mounted on the. carria-ge, fluid-pressure operated means for moving the carriage to efiect. a dressing operation com.- prising a cylinder and a piston reciprocable therein, one of which is. connected to the support and thezother to the carriage, a reversevalve for? controlling, the direction ofapplication of fluid-pressure to the piston, a shuttle valve; a duct connecting the reverse valve with one'side. or the piston, a duct connecting the other side. of the piston with the shuttle valve, two ducts connecting the shuttle valve with the reverse. valve, means constantly urging the shuttle valve in one. direction to connect one of the two ducts With the duct that leads from the shuttle valve to, one side of the piston, means actuated by the carriage at a predetermined point in its movement in: one direction for shifting. saidshuttle valve against the resistance of the last named 

